According to the prior art of a grinding wheel assembly disclosed in the FIGS. 4 and 5 of U.S. Pat. No. 7,147,550, the grinding wheel assembly, adopted for use on pneumatic tools, includes two clamping disks, a grinding wheel and a fastening element. The first clamping disk has a plurality of first anchor plates and a plurality of first anchor slots on one side. The first anchor plates and the first anchor slots are located on different perimeters in an alternate manner. The second clamping disk has a plurality of second anchor plates and a plurality of second anchor slots on one side. The second anchor plates and the second anchor slots are located on different perimeters in an alternate manner. The first anchor plates correspond to the second anchor slots. The second anchor plates correspond to the first anchor slots. The first anchor plates and the second anchor plates can be wedged respectively in the second anchor slots and the first anchor slots so that the first clamping disk and the second clamping disk form a mechanical interference with each other to achieve an anchoring effect. A fastening element is provided to run through the first hollow duct and the second hollow duct to fasten the grinding wheel to a pneumatic tool.
Somehow, there are following certain disadvantages from the prior grinding wheel assembly mentioned above:
1. The first anchor plates 110 of the first clamping disk 100 are inserted into troughs 310 formed on the grinding wheel 300, and the second anchor plates 210 of the second clamping disk 200 are inserted into a round opening 320 formed in the center of the grinding wheel 300. Apparently, there is no mechanical interference between the second clamping disk 200 and the grinding wheel 300 so that the structural strength of the grinding wheel assembly is weak.
2. The ventilation is poor due to lack of ventilators between the clamping disks 100/200 and the grinding wheel 300. When the pneumatic tool drives the grinding wheel 300 to rotate too long, the overall structure of the grinding wheel assembly is prone to be overheated because of the insufficient air circulation within the grinding wheel 300.
3. The coupling head of the pneumatic tool can only be fastened onto one side of the first clamping disk 100. When the grinding wheel 300 rotates for a long period of time, its outward wheel will be worn out more than the other side, causing the unbalance of the wheel and affecting the stability while rotating.
4. The clamping disks 100/200 can only fit onto one size of the grinding wheel 300. When the grinding wheel 300 needs changing to different size, it increases the cost to change the clamping disks 100/200 as well.